President Obama makes his way to board Marine One on the South Lawn of the White House on Feb. 19 as he heads to Mexico. / Mandel Ngan, AFP/Getty Images

by Aamer Madhani, USA TODAY

by Aamer Madhani, USA TODAY

President Obama condemned the deadly violence in the Ukraine on Wednesday and warned the Ukrainian government that "there will be consequences if people step over the line."

"We hold the Ukrainian government primarily responsible for making sure that it is dealing with peaceful protesters in an appropriate way, that the Ukrainian people are able to assemble and speak freely about their interests without fear of repression," Obama said soon after arriving in Toluca, Mexico, for a summit. "And I want to be very clear as we work through these next several days in Ukraine that we're going to be watching closely and we expect the Ukrainian government to show restraint, to not resort to violence in dealing with peaceful protesters."

Obama added that the United States expects protesters to remain peaceful.

"The United States will continue to engage with all sides in the dispute in Ukraine, and ultimately our interest is to make sure the Ukrainian people can express their own desires," Obama said.

Senior aides floated the possibility Wednesday of imposing sanctions against Ukraine in the aftermath of violence that has killed at least 25. The political violence is the worst the ex-Soviet republic has faced since becoming an independent nation in 1991.

The latest unrest flared after President Viktor Yanukovych refused on Tuesday to allow a vote on a law that would have reinstated limits on his powers.

The bigger point of contention centers on tensions over Yanukovych leaning toward a closer alliance with Russia, which is ready to resume providing loans to help the country's ailing economy. The protesters want the government to form an alliance with the European Union instead.

Late Wednesday, Yanukovych's office announced it had reached a truce with opposition leaders to allow for negotiations to restart to end the standoff.

The White House weighed in on the possibility of U.S. sanctions as the European Union announced it would hold "extraordinary" talks on the crisis. Polish Prime Minister Donald Tusk has called for EU sanctions against Ukraine in a special session of the Polish parliament.

"We have made it clear we would consider taking action against individuals who are responsible for acts of violence within Ukraine," said White House deputy national security adviser Ben Rhodes. "We have a tool kit for doing that that includes sanctions."

Rhodes told reporters traveling with Obama on Air Force One that administration officials hope to use the threat of sanctions to induce better behavior.

"Events like what we saw yesterday are clearly going to impact our decision making," Rhodes said.

Sen. John McCain, R-Ariz., and Sen. Chris Murphy, D-Conn., said in a joint statement Wednesday that they are crafting legislation for targeted sanctions against Ukrainian government officials and others complicit in the violence.

"We have consistently made it clear, including during our joint visit to Kiev in December 2013, that there must be consequences for the escalation of violence in Ukraine," the senators said. "Unfortunately, that time has now come."

Rep. Ed Royce, R-Calif., chairman of the House Foreign Affairs Committee, called on Obama to take action in Ukraine. Last week, the House voted in favor of a resolution calling on the administration to impose targeted sanctions against those responsible for the violence.

"The president should act now, without delay, before more are killed in the streets of Kiev and elsewhere in Ukraine," Royce said.

Sen. Marco Rubio, R-Fla., a member of the Senate Foreign Relations Committee, called on Obama "to use every diplomatic means at its disposal, including sanctions, to bring accountability to those involved in acts of violence throughout Ukraine."

Vice President Biden spoke by phone with Yanukovych on Tuesday to express "grave concern" about the violence, according to the White House.

Yanukovych blames opposition leaders for the eruption of violence in central Kiev.